Yusuf H K, Pohlentz G, Sandhoff K
J Neurosci Res. 1984;12(2-3):161-78. doi: 10.1002/jnr.490120205.
The synthesis of gangliosides GM1 and GM2 in intact rat liver Golgi vesicles is stimulated by phosphatidylglycerol as much as or even more than by detergents (Triton X-100 and octyglucoside, respectively). The antibiotic tunicamycin, known as an inhibitor of the N-glycosylation of proteins, strongly inhibits the synthesis of the above gangliosides, in the presence as well as in the absence of the phospholipid. Both phosphatidylglycerol dependence and tunicamycin inhibition disappear when the Golgi vesicles are solubilized by addition of detergents or disrupted by ultrasonication or pretreated with pronase. Transport studies with UDP-[3H]Gal show that tunicamycin blocks the penetration of the sugar nucleotide into the Golgi vesicles in a concentration-dependent manner up to 80%. The results show that tunicamycin inhibits ganglioside biosynthesis by blocking the transport of the nucleotide sugar and not by inhibiting the transferase directly. Studies on glycoprotein-galactosyltransferase with ovalbumin as exogenous acceptor showed that phosphatidylglycerol does not destroy the integrity of the Golgi vesicles. So this phospholipid is an excellent tool for studying ganglioside biosynthesis at optimal transferase activities without solubilizing the Golgi membranes.
完整大鼠肝脏高尔基体囊泡中神经节苷脂GM1和GM2的合成受磷脂酰甘油的刺激程度与洗涤剂（分别为 Triton X-100 和辛基葡糖苷）相当，甚至更高。抗生素衣霉素是已知的蛋白质N-糖基化抑制剂，无论有无磷脂存在，它都能强烈抑制上述神经节苷脂的合成。当通过添加洗涤剂使高尔基体囊泡溶解、通过超声处理破坏或用链霉蛋白酶预处理时，磷脂酰甘油依赖性和衣霉素抑制作用均消失。用UDP-[3H]半乳糖进行的转运研究表明，衣霉素以浓度依赖性方式阻止糖核苷酸进入高尔基体囊泡，最高可达80%。结果表明，衣霉素通过阻断核苷酸糖的转运而非直接抑制转移酶来抑制神经节苷脂的生物合成。以卵清蛋白作为外源受体对糖蛋白 - 半乳糖基转移酶的研究表明，磷脂酰甘油不会破坏高尔基体囊泡的完整性。因此，这种磷脂是在不溶解高尔基体膜的情况下以最佳转移酶活性研究神经节苷脂生物合成的优良工具。
